There are many techniques for molding that involve the use of preforms. One example of such a technique is structural reaction injection molding (SRIM). However, preforms with complex or intricate shapes may be difficult and/or time consuming to manufacture. As such, costs and energy consumption of such manufacturing processes may be undesirably high. For an enclosed or tubular preform, for example, some techniques involve generating multiple pieces of the preform separately, and then stapling or otherwise adhering the preform pieces together for subsequent processing. In another example, preforming utilizes an articulated screen, which may also undesirably add to the cost of preforming. Furthermore, there may be some geometries, such as an S-shaped or otherwise curved tube with a non-constant cross-section, which are not amenable to being formed via these methods.